Sergei Vladimirovich Kolesnikov is a Russian businessman who has lived in self imposed exile outside Russia since 2010. He is best known as a whistleblower after his December 2010 letter to Dmitry Medvedev, which exposed a corrupt scheme that included the construction of 'Putin's Palace' and challenged the Russian president to fight corruption. After he left Russia, his revelations of large scale corruption in President Putin's inner circle led to investigations in major Western media.